一律 / 一概【yílǜ / yígài】

一律 and 一概 go after the subject and before the verb, and say that what follows holds for every member of the group with no exceptions. They belong to rules, notices and firm statements.

一律 – a rule for everyone

一律 is the word of regulations: the same treatment for every person or thing in the group. It works with people as well as things, and with positive and negative verbs.

一概 – all of it, mostly negative

一概 sums up things and matters, rarely people, and most often goes with 不 or 没: 一概不知, 一概不管, 一概拒绝. It sounds blunter than 一律, a flat refusal more than a rule.

When the group is people, use 一律.

• × 学生一概要参加 → 学生一律要参加

Word order

Both are adverbs, so they sit after the subject. Putting them first, like English "all", is wrong.

• × 一律学生要穿校服 → 学生一律要穿校服
• × 一概我不知道 → 我一概不知道